Gale Warning 650, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AKDT SAT SEP 11 2010

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL RIDGE STRETCHING FROM THE EASTERN ALEUTIANS TO THE
NORTH SLOPE CONTINUES TO STRENGTHEN AS IT SLIDES SLOWLY EASTWARD.
MEANWHILE...A LOW IS DEVELOPING SOUTH OF SHEMYA AND IS MOVING TO THE
NORTH. ANOTHER LOW IS VERTICALLY STACKED AND NEARLY STATIONARY OVER
THE QUEEN CHARLOTTE ISLANDS. OVER MAINLAND ALASKA...AREAS OF FOG
FORMED OVERNIGHT AND ARE SLOWLY DISSIPATING OVER COOK INLET...THE
COPPER RIVER BASIN...AND SOUTHWEST ALASKA.

.MODEL DISCUSSION...MODELS ARE IN UNUSUALLY GOOD AGREEMENT IN HOLDING
SOME FORM OF UPPER LEVEL HIGH PRESSURE OVER THE STATE THROUGH THE END
OF THE WEEK. THE LONGWAVE TROUGH CURRENTLY OVER THE WESTERN BERING
SEA WILL SLIDE EAST TO INCLUDE ALL OF THE BERING SEA BY LATE
SUNDAY...BUT EASTWARD PROGRESS WILL HALT AS INTERIOR HIGH PRESSURE
HOLDS FIRM. THE RIDGE WILL ALSO FORCE THE DEVELOPING LOW PRESSURE
SOUTH OF SHEMYA TO HEAD RAPIDLY DUE NORTH AND INTO RUSSIA BY SUNDAY
EVENING.

.SHORT TERM FORECAST...
.SOUTH AND EAST OF THE ALASKA RANGE...UNSEASONABLY PLEASANT WEATHER
WILL CONTINUE THROUGH THE END OF THE WEEK. PROBLEMS WITH OVERNIGHT
FOG WILL CONTINUE IN THE COPPER RIVER BASIN AND IN SOME COASTAL
AREAS...BUT SHOULD DIMINISH IN EXTENT AND SEVERITY EACH NIGHT AS THE
LOWER LEVELS OF THE ATMOSPHERE CONTINUE TO DRY OUT UNDER LARGE SCALE
SINKING MOTION. MAY SEE AN ISOLATED SHOWER THIS AFTERNOON AND EVENING
OVER THE TALKEETNA MOUNTAINS...BUT SHOULD BE LAST DAY WITH ANY
NOTABLE CONVECTION AS THE LOW LEVEL CAPPING INVERSION IS EXPECTED TO
INTENSIFY.

.WEST OF THE ALASKA RANGE...HIGH PRESSURE RIDGING TO RETREAT SLOWLY
EASTWARD...BRINGING LIGHT SOUTHERLY WINDS TO MOST OF THE AREA
BEGINNING SUNDAY. WILL LIKELY SEE FOG REDEVELOP ACROSS THE AREA
OVERNIGHT BEFORE WINDS INCREASE. BEGINNING LATER SUNDAY...MAIN
CHALLENGE WILL BE KEEPING UP WITH MARINE LAYER FOG THAT MAY LINGER
PRIMARILY ALONG COASTAL AREAS FOR NEXT SEVERAL DAYS. THE FRONT
ASSOCIATED WITH A FAIRLY STRONG BERING LOW WILL RAPIDLY WEAKEN AS IT
APPROACHES THE COAST MONDAY NIGHT...AND WOULD NOT EXPECT ANYTHING
MORE THAN A FEW SPRINKLES.

.BERING SEA/ALEUTIANS...THE IMPACTS OF A MODERATE 984 MB LOW MOVING
QUICKLY THROUGH THE BERING WILL BE ENHANCED BY THE PRESENCE OF STRONG
HIGH PRESSURE TO THE EAST. A STRONG PRESSURE GRADIENT OVER THE
CENTRAL BERING AND ALEUTIANS SHOULD BE MORE THAN ENOUGH TO GENERATE
STORM FORCE WINDS TONIGHT AND TOMORROW AS THE LOW CENTER RACES TO THE
NORTH. WITH AMPLE WARM AND MOIST AIR BEING TRANSPORTED NORTHWARD WITH
THE JET...RAIN WILL LIKELY BE HEAVY AT TIMES ACROSS THE CENTRAL
ALEUTIANS WITH THIS SYSTEM.

.LONG TERM FORECAST...SUNNY AND WARM CONDITIONS PERSIST ACROSS MOST
OF MAINLAND ALASKA THROUGH THE END OF THE WEEK. ANOTHER STORM
APPROACHES THE WESTERN ALEUTIANS MIDWEEK...AS THE LONGWAVE TROUGH
REMAINS IN PLACE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...STORM 172 175 185
         GALE 170 179 180
FIRE WEATHER...NONE

AMD SEP 10